Chemical Activation and Nonequilibrium Unimolecular Reactions of C2H5Cl and 1,2-C2H4Cl2 Molecules

Abstract

A gas-phase chemical activation technique employing the H and Cl abstraction reactions by methylene from chloromethanes has been developed for the production of chloroethanes in the energy range between 85 and 95 kcal mole−1. In this paper the results from the reaction of methylene with chloromethane are reported. The abstraction reactions serve as a clean source of methyl and chloromethyl radicals; combination of these radicals at 25°C produces C2H5Cl and 1,2-C2H4Cl2 at energies near 90 kcal mole−1. Since the critical energy for the unimolecular HCl elimination reactions is about 55 kcal mole−1, the molecules will react by this pathway unless deactivated by collisions with the bath molecules. By studying the system in the appropriate pressure ranges, the nonequilibrium rate constants were measured at 25°C as 3×109 and 1.8×108 sec−1 for C2H5Cl and 1,2-C2H4Cl2, respectively.

Analysis of the chemically activated CH2Cl/CH2Cl and CH3/CH2Cl recombination reactions at elevated temperatures using the bimolecular Quantam Rice-Ramsperger-Kassel (QRRK) method

“…(5) ch4 kcal/mol, as suggested by Hassler and Setser (1966). This increased the relative importance of reaction 2 with respect to the other channels and rendered the HC1 elimination process as the major reaction pathway above 1200 K, which appears more plausible in view of the experimental data on the CCOP process (Granada et al, 1987).…”

“…It must be noted that the experimental and detailed RRKM (Rice-Rampsperger-Kassel-Marcus) analysis of chemically activated recombination reactions of CH2C1 and CH3 at low temperatures, when only one decomposition channel is accessible, exists (Hassler and Setser, 1966;Hassler et al, 1966). However, with the exception of a brief note by Tavakoli and Bozzelli (1987), we are not aware of 0888-5885/88/ 2627-0447$01.50/0 such studies at higher temperatures under which multiple decomposition channels become accessible to the chemically activated adducts.…”

Unimolecular HCl Elimination from 1,2-Dichloroethane: A Single Pulse Shock Tube and ab Initio Study

“…The decomposition of 1,2-dichloroethane (1,2-DCE) has received enormous attention over the last five decades. The literature on this reaction can be arbitrarily divided into fundamental − and applied − studies. All the “applied” studies concern themselves with improving the production of the vinyl chloride, which is the raw material for the manufacture of the industrially important poly(vinyl chloride), PVC.…”

“…(The activation energy and barriers are given in kcal mol -1 here and throughout the paper). Setser and co-workers assumed that the HCl elimination barrier from 1,2-DCE would be equal to that of EC, but cautioned that it may be a lower limit . In fact, Dees and Setser 6 later on suggested that the HCl elimination barrier for 1,2-DCE should be higher than that of EC.…”

Experimental and theoretical study on the kinetics and mechanism of thermal decomposition of 1,2-dichloroethane

“…Hassler et al [16] considered falloff behavior for reaction R1 and pointed out that, at 1.3 atm, this reaction is in highpressure limit at 600-1500 K. Kara and Senkan [17] have analyzed the falloff behavior of CH 2 Cl + CH 2 Cl from 0.5 atm up to 10 atm and T = 500-1700 K. They pointed out the lack of experimental data on the falloff behavior of reaction R1 and cautioned that their results await experimental verification. Incavo [9] studied 1,2-dichloroethane cracking to vinyl chloride in the presence of CCl 4 and Cl 2 at 500 K. He reported different byproducts including methyl chloride and methylene chloride.…”